Dioscorea orangeana (Dioscoreaceae), a new and threatened species of edible yam from northern Madagascar

Abstract

A new species of yam (Dioscorea orangeana Wilkin) is described and illustrated. It differs from D. comorensis R.Knuth by having undulate leaf margins and a broader torus and tepals in both the male and female flowers. In female flowers of D. orangeana the floral stipe between the ovary and the torus is shorter than in D. comorensis. The tuber morphology of the species is atypical among Malagasy species in that there are several digitate lobes rather than a single tuber per growing season, although more research is needed on tuber morphology. D. orangeana is reported to be edible. It is endemic to the Foret d’Orangea near Diego Suarez (Antsiranana) in Antsiranana Prefecture. Its conservation and sustainable use are thus matters of concern.